Block and panel caving is an efficient technique that uses gravity to extract ore from an ore body. Caverns of broken rock are blasted at an upper level beneath the ore body to be recovered, extraction tunnels are formed at a lower level there below and a series of relatively narrow drawbells are blasted between the upper and lower levels to allow broken cavern rock to fall through the drawbells into the underlying extraction tunnels, through which the rock can be removed. A description of block caving is found in the background of International Publication NO. WO2011/100808 by Technological Resources Pty Limited entitled “Underground Mining” and the method of rock blasting is described in the background of US Patent Publication No. 2012/0242135 by Thomson et al. entitled “Method of Underground Rock Blasting”.
The extracting of the ore from the draw points and its delivery to a crusher is conventionally carried out by an autonomous guide vehicle (AGV) known as Load Haul Dump (LHD) unit. These units are typically semi-automated and remotely controlled by an operator. The problem with this method is that each load carried by an LHD unit takes several minutes due to the travel distance between the draw point and the crusher. To achieve high tonnages many LHD units are required and because they are large machines, traffic management becomes an issue and “bottlenecking” around the crusher and shared drives limits production.
Each LHD unit typically has a front bucket for loading and carrying ore, and the size of this bucket generally determines the width of the vehicle. In many block caving operations the tunnels have a width of about 5 m, and two LHD units cannot readily pass each other. Typically an LHD will be brought into a branch tunnel or park bay in order for another LHD to pass.
The present invention seeks to overcome at least some of the abovementioned disadvantages by providing apparatus, method and system for extracting ore from block caves.